Description: The Tissue Culture Core is intended to be a centralized service facility to perform the cell Culture work and to maintain standardization and quality control. It will serve the majority of the program investigators. The specific aims of this service core are to 1) grow and maintain specialized cell lines to be used by multiple investigators; 2) prepare large quantities of certain cells for biochemical studies in individual projects; and 3) provide small amounts of intestinal cells to other investigators both within and outside of Johns Hopkins University. Although the Core is largely a service core, it also will continue to serve a more minor role to train investigators using intestinal epithelial cells to culture cells. Daily work (e.g. maintenance of cell lines, preparation of experimental setups, medial preparation) is performed by Mr. Dwight Derr. The Quantity of daily work is defined by the written requests from each Project leader. This allows coordination of the work, achievement of maximal efficiency and cost accounting for the work performed. Strict rules are in place requiring all users to adhere to biosafety level 2 precautions and to use sterile technique at all times in the facility. Mr. Derr consults as necessary with Dr. Sears regarding any questions or problems arising in the Tissue Culture Core.